Magneto-resistive head asymmetry (MRA) in a hard disk drive may cause the read-back signal to become distorted, causing losses in system performance. MRA may be due to improper bias current setting(s) during calibration, due to changes in the physical head characteristics of the read head, or due to other system inaccuracies. MRA may be estimated by is measuring peaks of low frequency patterns, however such techniques are typically relegated to in-factory measurements not suitable for real-time in the field applications. Accordingly, there is a need to provide a method and system to estimate MRA in real time.